Tank vent



P. S. SHIELD Dec. s, 1,927'. 1,651,971'A TANK VENT Filed March 7. 1924 3w8. 11n/Emol?A Patented Dec. 6, 1927.

'UNiTED s-Txrns.v

1,651,971 PATENT' OFFICE.

PAUL S. SHIELD, OF CINCINNATI, OHIO, ASSIGrNOR T AUGUSTINE DAVIS, JR.,OE;V Y COVINGTON, KENTUCKY.

TANK VENT.

Application led March 7, 1924. Serial No. 697,430.

` The invention relates to` vvalved tankvents for relief ,of positiveand negative pressure in the tank. It isV necessary in a vent for use ongasoline containers, or eX- ample, that the vent have at leasttwofunctions, one to relieve internal pressure whenever it is developed,as for, instance fron'r the heating of the contents due to exposuretothe sun, the other to provide for the ad;

mission of air when the contents are being drawn off, and with regardtothe latter function, in particular', thc vent should have arsuiiicientcapacity to prevent any retard ing of the flow of the liquid through thedis charge line, which it may be noted is an objection applying to mostor' the tank wagon vents now on the market. This latter requirementinvolves not only Vthe provision of sulicient area in the air passages,but it also requiresthat the valves themselves be osuch character'as toreduce to a minimum the partial vacuum necessary to open the vacuumrelief. The purpose of the present inventionis to provide a vent, whichamong other advantages, satisr'iesv these requirements and is of asimple construction.

In the accompanying.drawings forming apart hereof; r Y

F ig. 1 is a central vertical section through a vent embodying theinvention, the valve' being shown seated in ulllines and raised, as i byinternal pressure, in dotted lines; and Y f F ig. 2 is ahorizontalcross-section onk the line 2-2of Fig. 1. e

The vent comprises a `body 1,'which may be Vcylindrical inl form, havinga. screwthreaded stem- Ql at its lower end for connection with a tank. Acentral longitudinal passage 3 extends ythrough the stem 2, and withinthe body part, and widens above into a number of counterbores orprogressive enlargements 4, 5, and 6. The chamberY 4. is

ar valve` chamber containing aV vertically' movable kvalve member 7,whichnormally rests upon avalve seat 8. Air passages 9 extend from thevalve chamber enlargement downwardlyA and outwardly through the wallof-the body, placingthe region 4, 5 in free communication with theatmosphere.`

The construction of vthe vent is such that there may be any desiredVnumber of rthese passageshaving anample total keiective area comparablewith'the area of thepassage 3.

- vent for vacuum relief.

through the valve member 7, the valve member-.being slidableupward'onthe stem, the pistonremaining stationary, as indicated by the dottedlines of Fig. l. A collar 13 on the piston stem,l below the valve, formsa one-r way connection venabling the valvek to be lifted bythe piston.when the latter rises. The top of the chamber 6 is shown tightly closedby a screwcap 14.' The chamber` 6 will be termed a closed chamber, sinceit is cut oli from the pressure of the atmosphere outside the tank, buta passage is provided which `'maintains communication between thischamber and the air space in the etop` of thetank. In the drawing thispassage is simply and'advantageously contrived by making the stem l2hollow throughout its length, the upper end of the passage 15 thusprovided opening into the chamber 6 above the piston and the lower. endopening into the passage 3. y

VThe voperation is as follows:

If positive pressure occurs Within the tank,

such pressure liftsthe valve 7 upward along theV stem 12, and the excesspressure escapes to the atmosphere vthrough the lateral passages 9.;Vhenv Vthe pressure has been relieved the valve is automatically seatedagain by gravity or otherwise. t may be noted that there is no tendencyfor the4 piston` 10 and` its stenrl?. to rise under positive pressure inthe tank, because the pressure is communicated through the passage 15 tothe chamtop area of the piston. In case of partial vacuum, thatis tosayfr reduced pressure within the tank, the valve is moved in the sainedirection as under positive pressure. This is effected through thechamber 6, then acting as anegative pressure chamber, and the pis- -ber6 and acts downwardly uponthe large ton 10, overcoming the pressure ofthe at'-` mosphere, whichthen tends to hold the valve to its sea t, thearea of the piston 10y being so muchlarger than the area ofthe-valvemember, however, that it requires only slight reductioninpressure in thetank toopen the 7, onceliftedby the piston 10., remains lifted The valvemembery as long as the negative. pressure condition exists, owing to the'act that the inrush of air to the tank past the lower end of thepassage l5 maintains or augments the vacuum etliect in the chamber 6. Itmay be noted that the base or the piston chamber forms a close-littingrseit for the bottom ot the piston, so that even atter some slight wearon the sides ot the piston has taken place the `initial vacuum necessaryto start the piston upward is developed against a tight joint.

lhen the` piston is raised in response to negative pressure, therebyopening the valve, the chamber (l remains closed or substantially closedto diiect communication with the atmosphere. This results :troni the litof the piston in the c-yliiulrical wall ot the chamber 6, any slightleakage around the piston being inconseqneiitial, and 'trom the tactthat the connection between the passage 15 and the chamber (l above thepiston remains unbroken. The suction o't the air rushing;r into the taknpast the open lower end ot' the passage l5. which is extended downward asubstantial `distance below the valve, serves to maintain or prolong thevacuum ctlect in the chamber (i to insure wide and sustained opening ofthe valve permitting: tree entrance of air in order that drawinor olliot liquid from the tank shall not be retarded, insuring also that thevalve will not close prematurely `bcifore normal pressure in the tankhas been sull'iciently restored, and in general insuring that? the valvewill act promptly and elliciently at all times and under all conditionscallingl for negative pressure relief.

This concludes a `description ol the best 'form ol"` the invention nowknown to me. I wish it to be understood, however, that numei-ous changesin forni, proportions, ar-` rangements, details, and by way ot additionsor omissions or substitution et equivalents. may be made withoutdeparting from essentials.

lVliat I claim as new is:

`l. A" tank-vent containing` a valve me1n ber adapted to vicld topositive tank prersure to permit the escape of excess pressure ronrthetank, a chamber, and means respon sive to reduced pressure in saidchamber to move said valve member in the same direction as in the caseot excess pressure, in or der to admit external pressure to the tank.

2. A tank-vent containinga valve member adapted to yield to positivetank pressure to permit the escape ot excess pressure troni the tank, achamber, a member movable in iespense to reduced pressure in saidchamber, and a shouldered stein itorniing an operative connectionbetweensaid member andisaid` valve member to move said valve member in thesamedirection as in the case of excess pressure, in order to admit externalpressure to the tank, said stem and one ot" said menibers being;1 tree:tor relative movement when the valve member yields to excess pressure.

C-l. A tank-vent containing a valve member adapted to yield to positivetank pressure to permit the escape ot excess pressure from the tank, acliaiiiber, a member movable in response to reduced pressure in saidchani bei', and a shouldered stem toi-mingl an operative connectionbetweeii said member and said valve member to move said valve membei' inthe saine diicction as in the case o'lE excess pressure, in order toadmit `external pressure to the tank, said stem being hollow` andatlori'ling` communicatiim between said chamber and the tank.

A tank-vent comprisingi a body having 'a tank connection passage,lateral vent pas "is, a valve seat between thetank connecn passage andthe lateral passages, a valve member .normally res-tine against saidseat and adapted to be moved therefrom by ex cess pressure in the tank,a chan'ilier beyond `the valve member in communication with the tank, amember adapted to respond to reduced pressure in said chamber. and ashouldered rod between said member and said uilve member to more saidvalve away from said scat when a reduced pressure condition occurs insaid. chamber, the valveniember being movable relatively to said otherincmbei' under excess pressure in the tank.

5. A vent having' a valve seat, a valve member normally closed againstsaid seat and tending to be held closed by the external pressure thereonwhenthe pressure in the space to be vented is lowered, a. chambei'havinimT means ol communication with the said space, and meansassociated with such chamber and operating to move said valve memberaway 4rom said seat when the pressure in said chamber is lowered.

(i. A. vent having a valve scat, a` valve member normally closed againstsaid seat and tending to be held closed by the exter nal pressurethereon when the pressure in the space to be vented islowcrcd, a chamberhavinriI means oll communication with the said space, and meansassociated with such chamber and operatingl to move said valve memberaway from saidseat when the pres-` sure in said chamber is lowered, therelation between the passagrefor the admission ot air to said space andthecommunication way between said chamber and saidspace beine' such thatthe inrush ot air operates to maintain a vacuum etlileet in said chambertemporarily.` y y i 7. A vent having,Y a seat, a valve member normallyclosed against said seat and'adapt-- cdto be moved away `from saidseatby ex cess pressure in the space to be vented to permit suchpressure to escape, andineans tor employiingr reduction in pressure in`such space also to unseat said valve member, the

Tll

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movement of the valve in both cases being in the same direction. c

8. A vent having a valve for relieving both positive and negativepressures in a space to be vented, said valve member opening away fromand seating toward such space so as to yield directly to positiveinternal pressureV in said space, and means responsive to reduction inpressure in such space-and of superior power to the external pressureacting `on said valve member, so as to unseat saidl valve member when acondition or reduced pressure occurs in said space. f

A vent having a valve member for relieving both excess and minuspressure vin the vspace to be vented, and means whereby said .valvemember moved in the Vsame direction to open the vent by Virtueoif either.atmosphere canraisc said member, and an operating)` connection between.said operating member and said valve member :tor littl ing the latter.

ll. A tank vent containing a. valve seat, a valve member which closesdownward againstsaid seat, a chamber above said valve member, anoperating ^member associated with said chamber and adapted to be vraisedwhen negative' pressure is-Y communicated romthe tank to saidchamber,there being a commifmication from the outside atmosphere to thespace beneath said operating member so that the pressure of theatmosphere can raise said member, and a hollow stein extending downwardtrom said operating member and radapted to litt said valve member, the

verticalv passage. through said stem com` municating at' the upper endwith theinterior ot saidchamber, and the lower end of said passagecommunicating with the space between said valve member. p

l2. A `tank vent containing a valve seat,

aV valve member which closes downward against said seat, a chamber abovesaid valve member, an operating member associated with said chamber andadapted to be raised when negative pressure Vis communicated trom thetank to said chamber, there being acommunication from the voutsideatmosphere to the space beneath said operatingl member so that thepressure of the' atmosphere can raise said member, and a hollow steinextendingdownward from said operating member and adapted to lift. saidvalve member, the vertical passage through said stem communicating atthe upper end with the interior of said chamber, said passage having atubular extension at the lower end projecting a substantial distancedownward below saidV valve member in order `that iiirush of air pastsaid extensionwill operate to maintain a vacuum effect in said chambertemporarily.

18. A tank vent containing a valve seat, a valve member which closesdownward .against said seat, means forming a chamber above said'valvemember whereby negative pressure communicated from the interior of thetank to said` chamber causes said valve member to be lifted byatmospheric pressure, and means formingk a vertical passage through saidvalve member with a tubular extension projecting downward below saidvalve member, to maintain a vacuum effect in said chamber when saidvalve is lifted in response to negative pressure in the tank.

14. A tank vent containing ka valve seat, a valve member which closesdownward against said seat, means forming a chamber above said valvemember whereby negative pressure communicated from the interior oflthetank to said chamber causes said valve member tobe`litted byatmospheric pressure, and means forming al communication passage betweensaid chamber and the interior of' the tank, said passage being extendeddownward below said valve member anid opening into the space to bevented in such manner that inrush of air past the lower kopening of saidpassage will operate to maintain a vacuum effect -in .said chamber tem-kporarily, said chamber remaining substantially closed'todirectcommunication with Ythe atmosphere'when said valve member islifted. PAUL S. SHIELD.

